Operator to alter a first flow's last emitted value whenever the second flow emits. Transformation will take last value from both as in combine

alterOn.kt

/**
* Will emit all values from Flow<T1>, plus those from Flow<T2> after transformation giving the latest from Flow<T1>.
*
*/
fun <T1, T2> Flow<T1>.alterOn(other: Flow<T2>, transform: suspend (a: T1, b: T2) -> T1): Flow<T1> = channelFlow {
    coroutineScope {
        val thisLatestValue = AtomicReference<T1?>()

        launch {
            other.collect { t2 ->
                thisLatestValue.get()?.let { t1 ->
                    send(transform(t1, t2))
                }
            }
        }

        collect { t1 ->
            thisLatestValue.set(t1)
            send(t1)
        }
    }
}




// (Can also be acheived using flatMapLatest)